The present invention relates to a modular implant part for replacing a part of a natural knee joint with an implant component comprising a shaft extending away from the implant component and a connecting device for connecting the shaft to the implant component.
Furthermore, the present invention relates to a knee joint prosthesis comprising a first implant part in the form of a femoral part, a second implant part in the form of a tibial part and a third implant part in the form of a meniscus part, wherein the first and/or the second implant part is a modular implant part for replacing a part of a natural knee joint with an implant component comprising a shaft extending away from the implant component and a connecting device for connecting the shaft to the implant component.
Modular implant parts of the type described hereinabove are used in order to obtain particularly stable embedding of the implant in the bone. For this purpose, shafts in the form of extension shafts are used and they are inserted into a medullary cavity of a partially resected bone, for example, the femur or the tibia of a patient so as to enable the shafts and hence the implant part to be better supported on the bone. The shafts for the respective implant part are usually available in different lengths and angles. Moreover, in order to enable the position of the shaft relative to the implant component to be ideally matched to the anatomy of a patient, it is advantageous if the shafts are adapted to be mounted on the implant component in different positions.
Examples of modular implant parts of this type are known from U.S. Pat. No. 5,782,920, US 2003/0055508 A1 and U.S. Pat. No. 5,290,313. The disadvantage of the implant parts described in the aforesaid documents is, however, that the shaft can only be mounted on the implant component at defined angular positions or with a defined lateral displacement using appropriate adapters so that, in turn, a multiplicity of appropriate adapters is necessary for different positions of the shaft.
Consequently, it would be desirable to provide a modular implant part and a knee joint prosthesis of the type described hereinabove which would allow fixing the shaft the implant component at a multiplicity of desired positions in a simple manner.